Valves include plugs that engage seats to control fluid flow through the valve. The engagement between the plug and the seat may cause damage to the seat over time. In some examples, the seat becomes relatively soft when the valve operates at higher temperatures and relatively hard when the valve operates at lower temperatures.
The figures are not to scale. Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts.